The present invention relates to apparatus for building a continuous tobacco stream, particularly a stream which can be converted into a filler suitable for draping into a web of cigarette paper so as to form with the web a continuous rod which is thereupon subdivided into smokers' articles of desired length. More particularly, the invention relates to improvements in distributors which can be used in cigarette rod making machines to convert a mass of tobacco shreds and/or otherwise configurated tobacco particles into a continuous stream which is ready for draping or is ready to be advanced past one or more trimming or equalizing devices.
It is already known to form a continuous tobacco stream in an elongated channel which is defined by two sidewalls and an endless air-permeable tobacco transporting conveyor one side of which faces the channel and the other side of which is adjacent to a suction chamber serving to attract tobacco particles to the one side of the conveyor. The channel can receive particles of tobacco from a classifying device which segregates unsatisfactory particles from acceptable particles, and some of the particles which are admitted into the channel are often subjected to the action of air streams having components of movement in the direction of advancement of the tobacco stream with the conveyor. It is also known to admit particles of tobacco into the channel along an arcuate guide wall so that the particles enter the channel at a locus which is remote from the conveyor and travel across the channel toward the one side of the conveyor where they form a growing tobacco stream.
The provision of means for directing into the channel several air streams, which impart to certain particles of tobacco a component of movement in the direction of advancement of the growing tobacco stream, is desirable and advantageous because this contributes to homogeneousness of the tobacco stream. An ideal situation would develop if the particles of tobacco could be accelerated and oriented in such a way that no relative movement or minimal relative movement would take place between the conveyor and the particles which are in the process of accumulating thereon. Heretofore known apparatus are incapable of bringing about uniform, predictable and optimum acceleration and orientation of all tobacco particles before the particles reach the conveyor. The situation is close to ideal in a certain portion of the channel if the apparatus is constructed and assembled in a manner as disclosed in commonly owned U.S. Pat. No. 4,175,570 granted Nov. 27, 1979 to Uwe Heitmann. The patented apparatus is capable of ensuring highly satisfactory acceleration of tobacco particles adjacent to one sidewall by providing such sidewall with air guiding channels serving to admit streams of compressed air which propel the particles that are close to the one sidewall in a direction such that the extent of relative movement between the conveyor and the particles which were acted upon by the air streams is negligible or nearly zero. The air guiding channels are rather closely adjacent to the one side of the conveyor so that air streams which are conveyed therealong cannot influence each and every tobacco particle to an optimum extent.